Is using a tool that allows you to move via keyboard shortcuts allowed on lichess?

I recently ran into this tool on Lichess: github.com/Sentero-esp12/Lichess-Keyboard-Input

This is a google chrome extension that allows you to move via keyboard shortcuts (for example, press 'a' to move queen side knight to square that you're hovering over).

Is this tool legal to use on lichess.org/?

I don't have an answer for you. I looked at the GitHub repo (the README.md, the home page), and my first thought was:

"Imagine trying to adapt to that specific tooling, or however you want to map something for your needs."

Even if a specific chess-playing tool is available, adapting to it might be counter-intuitive, and require a possibly very long period of adapting. (Possibly long enough that most users might give-up such an effort; moving a mouse is easier unless you have good and readily adaptable fine-motor-control.)

On the other hand, no different than other gaming, such as FPS, MMO. You still have to learn to play the particular game if you're not aware of that game's particular shortcuts. Most people seem readily adaptable enough to adopt keyboard shortcuts to play games online via computer (versus console-specific hand-held device).

Ultra-bullet only really being possible from a technological point of view, not OTB, then it makes some sense in terms of natural evolution for top-level players. (Please correct me if I'm wrong, I don't play ultra-bullet; never seen anything such played OTB.)

From a purely technical perspective, I see nothing wrong with the tooling and tool-chain. Maybe it enables someone disabled to play? If you were to consider "accessibility" requirements, then linking into tool-chain like this makes perfect sense. Otherwise you exclude a class of players simply because of disability. Keyboard short-cuts are a way for those who might have a disability (i.e. blind) to play via secondary interface considerations.

And, on the near-horizon, consider things like BCI (Brain-Computer-Interface). It's still on the horizon, but at least we can see the horizon now. Imagine someone who is quadriplegic or who has locked-in syndrome being able to play chess?! I'd offer to shake that person's hand, but I'd probably receive a blink or an eye-twitch or Stephen Hawking voice in response.

Moving the pieces ... Read Art. 4.1 and 4.9 and 7.5.4 and 6.2.3
handbook.fide.com/chapter/E012018

My conclusion: Play fair, use only one hand, not two. Press the clock with the same hand you played your move.
Assume we should not be hovering our mouse with one hand and entering our moves with the other hand.

OTB I believe we can still write our moves with our right hand and play our moves with our left hand or vise versa.
Maybe one day, there could be a rule saying ... Do everything with the same hand. (Write, move & press button)

If your games end short of time, then think about picking games with increment time controls.
If you're going to try it, then pick your normal minutes per move that you prefer, and add a second of increment time and see what that does for your games. If that's not good enough, then add another second and so on ...

I like the 2 seconds increment time controls. When I play fast, I can maintain my clock minutes, like they were frozen in time. So I know I can play 0+2 games, but not 0+1.

I prefer increment time over extensions, because I can use increment time OTB, but not extensions.